This invention relates generally to protective covers for prepackaged foods and more particularly it relates to an openable cover adapted to be used in connection with an aluminum pan in which raw corn kernels are popped.
The packaging of foods in metal containers in which they must be heated for serving is a widespread practice. Among the food products packaged in this manner is raw corn kernels for making popped corn. Such packages contain dried corn kernels and cooking oil as well as salt, other flavoring agents and preservatives. The container is covered with an extensible aluminum foil and is provided with a handle. In the heating process, the pan is placed over a source of heat and the corn is popped within the pan causing expansion of the extensible cover.
The aluminum foil used in such a cover is of extremely thin guage, considerably thinner than the aluminum used for the bottom or sides of the pan. Owing to its thinness, the aluminum foil in the cover is susceptible to damage or perforations. It is therefore necessary to employ an additional cover over the top of the pan when it is offered for sale and the additional cover must be easily openable. Generally a paperboard cover is used and in addition to serving the protective function, it also permits display of advertising matter and identification of the product as well as directions for use. The paperboard cover is anchored in a sealed relation on the container by crimping a margin of the aluminum foil on both of the expansible top and relatively thick container sides.
Prior to heating the popped corn package, a major central part of the paperboard cover must be removed in order to permit the expansible aluminum top to expand through a remaining annular portion of the paperboard cover during the heating. This annular portion of the paperboard cover acts as a gasket for the pan and the thin expandable foil to reduce the loss of steam during popping thus causing the package to function successfully.
To facilitate the removal of the cover, one or more top scores extend on both surfaces of the cover around the peripheral portion thereof. The depth of the top scores is usually less than the depth of the paperboard cover. In order to define a finger tab there has been provided an angular cut or tab terminating in the outer peripheral cut score. When the finger tab is gripped and pulled, the paperboard cover is torn away along the cut score lines thereby exposing the expansible aluminum foil top and leaving, around the rim of the container, a narrow marginal band of paperboard.
A paperboard container cover that is provided with cut scores and an angular cut so as to facilitate easy removal of a major portion thereof, as described hereinabove, is disclosed in U.S. Pat. Nos. 3,043,680 and 3,110,233.
Openable paperboard covers disclosed in the above patents have been used for several years in connection with the popped corn producing containers. The angular cut shape defining a finger tab which acts as a starter for the lid opening and removal of the same has been used because it helps minimize the moisture vapor transmission and helps prevent accidental puncturing of the spun aluminum located underneath. Prior to using the angular cut shape, other die cut shapes were used; however, these proved faulty for one reason or another. Due to the fact that the angular cut or pull tab is normally in the plane of the upper surface of the lid, it has been necessary first to lift the sides of the angular tab. The delicate spun aluminum foil has been frequently punctured by a fingernail or other object when the lid opening process has been started. A small protective circular tab has been placed underneath the area of the angular cut but despite this precaution the above-mentioned probelm has still taken place.
It is therefore a primary object of this invention to provide a paperboard cover for prepackaged foods container which at the start of opening operation substantially reduces the danger of puncturing the underlying aluminum foil of the container.
Another object of this invention is to make the lid opening and removal easier.